First you need to define your function (Parameters--->function---->Define/edit) then save it. after that you need to read this function (Parameters--->function ---->Read from file).

After that when you apply your load dont put a constant value but you select the option : existing table instead of constant value

Dear Dr. Laidoudi Farouk,

Thank you for your valuable information and replay. I will try to use the function tool to apply the voltage load.

I have one more question if you do not mind, how can I apply the function into the selected nodes only ? or in other word how can I use the function in my commands ?

I have copied below the commands I used to select the nodes and to apply the static voltage for your reference:

!!!!!!!!!!!! Ground electrode

nsel,s,loc,z,0

nsel,r,loc,x,20e-3,40e-3

nsel,r,loc,y,20e-3,40e-3

cp,1,volt,all

*SET,ng,ndnext(0)

nsel,all

!!!!!!!!!!!! positive electrode

nsel,s,loc,z,0.5e-3

nsel,r,loc,x,20e-3,40e-3

nsel,r,loc,y,20e-3,40e-3

cp,2,volt,all

*SET,nl,ndnext(0)

nsel,all

/Solu

antyp,static,new

OUTRES,ALL,ALL

KBC,0

nlgeom,on

nsub,30

autots,off

TIME,E

d,ng,volt,0

d,nl,volt,V

your help is much appreciated.

After the definition of your function, use the D command to applly your load but put the name of the function instead of your constant value.